In many situations it is desirable to be able to determine a position on a surface. For example, it may be desirable to determine the position on the surface of a sheet of writing material of a pen point when the pen is used to write on the sheet, thereby facilitating recording and digitizing the document. It may also be desirable to determine a position of a surface when creating an electronic version of handwritten information.
U.S. Pat. No. 5,852,434 describes a device for determining the position of a pen with respect to a sheet of paper when the pen is used to mark or write on the sheet. The system relies on a writing surface bearing a position-coding pattern for determining X-Y coordinates. A detector on the pen detects the position-coding pattern and determines the position on the sheet of the point of the pen. A processor determines this position in relation to the writing surface based on the detected position-coding pattern. The device allows a user to input handwritten or hand-drawn information to a computer at the same time the information is written or drawn on the writing surface.
The difficulties associated with generating a positional pattern of thousands of dots are significant. The dot pattern must be generated and then printing instructions must be generated to control the printer in printing a large number of circles which are filled in as the dots. Drawing circles is process intensive and very time consuming. While such time consuming pre-printing operations may be acceptable when only a few sheets of writing material are to be printed by means of high speed presses, when the dot patterns are determined to vary from sheet to sheet and when the sheets are to be printed on laser printers of the type utilized in a business office or a home office, then the times associated with generating these patterns may become undesirably long. It is seen, therefore, that a need exists for a sheet of writing material that can be printed rapidly.